Pixar's 'Luca' sea-monster boys were inspired by iguanas, and there were originally three

The search for Pixar's perfect "Luca" sea monster started with ancient maps.

When director Enrico Casarosa formulated the coming-of-age story, inspired by his own childhood on the Italian Riviera, he zeroed in on the fearsome sea serpents on the edges of Renaissance maps waiting to gobble up ships that ventured too far.

Then Cararosa ventured to the wildly colorful to make his two teenage sea monsters for "Luca" (available Tuesday on Blu-ray and digital).

"The point of the story is the two factions, humans and sea monsters, think of the others as monsters, not themselves," says Casarosa. "We knew there had to be a certain beauty and brought the iridescence."

Here's what you need to know about the shimmery monster stars, Alberto and Luca (voiced by Jack Dylan Grazer and Jacob Tremblay).

Review: Pixar's 'Luca' delivers an Italian-flavored Disney+ delight for kids of all ages

Originally, there were going to be three sea-monster boys

Pixar had plans for three sea-monster boys. "The duo was a trio," Casarosa says, introducing a deleted scene from the "Luca" Blu-ray.

Casarosa shows off the third character Ciccio, who was "this kind of this third-wheel, odd kid."

But the character "was stealing away from the main relationship," the director says. Ciccio had to be cut from the sea monsters. But the odd character returned to "Luca" in human form, as part of bully Ercole Visconti's all-human gang terrorizing the sea monsters.

The film's "Festa del Mare" scene, without Ciccio, was redone with just Alberto and Luca.

Sea iguanas were key to monster sea movement

With limbs added to the ancient sea serpent concept, the Pixar animating team found movement inspiration in sea iguanas. "Iguanas are pretty fascinating, the way that they use their tail from side to side, tucking away the limbs," says Casarosa.

That required watching as much iguana swimming footage as possible, and much trial and error. "We kept on honing in and found what felt right with the iguana reference," says Casarosa. "We really had to invent it as animators."

No to 'creepy' squid hair, yes to shimmering paddles

Finding the right hair was an entire project, with squid-like tentacles as curly hair thrown out early in the process.

"We realized it was a little too creepy, you start thinking the hair is alive," says Casarosa.

Instead, the animators landed on individually modeled, sculpted hair paddles of brilliant Mediterranean colors that move and shimmer under water.

"It was really fine-tuning physics, computer and artist working on these paddles for the hair, which made them so fluid and flowing. I loved it," says Casarosa.

Octopus legs were tossed overboard

Early designs featured tentacle-like legs, as from squids and octopi. These were set aside as too villainous for the Pixar creation.

"It felt like the evil witch (Ursula) from 'The Little Mermaid,' That didn't fit," says Casarosa.

Instead the animators went to more human legs with fins on the back, along with long, webbed feet and hands.

Sacha Baron Cohen put strange voice to odd Uncle Ugo

The Pixar team went deep designing Uncle Ugo, who emerges from the unplumbed ocean depths to warn Luca of the terrors of the human-filled surface. The bizarre looking angler fish served as the inspiration for Ugo, an odd character thrilled to be living in the darkest part of the ocean.

Ugo transformed from pale to transparent during the design process, with his beating heart weirdly visible.

"That transparency was so much fun, even if it was technically hard," says Casarosa. "But the team nailed it."

The glowing eyes were added accidentally during an early character draft. The director loved the look and kept it.

"We realized that Ugo's eyes should always be glowing, so those glowing eyes were a little bit of what Bob Ross calls 'a happy accident,' " says Casarosa.

Cohen added his own out-there interpretation of Uncle Ugo's voice in the recording studio — featuring an indistinguishably bizarre accent while instilling an "almost machoistic" love of the lonely deep," Casarosa says.

The film's final post-credit scene shows Ugo riffing about life in the dark. This was animated entirely around Cohen's sustained studio improv and added to the end.

"Sacha is such an amazing improviser, he came into the studio and gave us so much material," says Casarosa.

Many have placed their meaning into the sea monsters turned human

"Luca" follows the young boys secretly emerging into a human world — filled with misunderstanding, bigotry and hatred — and coming to acceptance of their identity. This has led to questions over whether "Luca" is telling a deeper story — perhaps its the first gay Pixar movie?

Casarosa welcomes the thought and discussion, but says that was not the story's original intent.

"I love the metaphor of the sea monster, that it really opened it up to all these other readings," says Casarosa. "I've had people ask me, is it a refugee story or immigrant story, or about race? We were aware making the movie that this was a wonderful journey of owning your own identity, and coming out with it — whichever that identity is. I thought that everyone would bring their own identity to it."

"My experience was about me and my best friend growing up feeling like losers," he says. "But it's great that people have their own experiences and that this speaks to them."

This article originally appeared on USA TODAY: Pixar's 'Luca' deleted scene: This sea monster got cut from the film